Abstract 14009: Plasminogen Activator Inhibitor-1 (PAI-1) is an Essential Driver of Cardiovascular Aging in Mice

Introduction: PAI-1 is the protein product of the gene Serpine1 . PAI-1 is a key contributor to cellular senescence in humans and mice, and elevated PAI-1 predicts the development of aging-related disorders including Type 2 diabetes and hypertension. GrimAge, a composite measure of epigenetic age, includes a DNA methylation estimator of plasma PAI-1 levels that independently predicts the development of cardiovascular (CV) morbidity including hypertension and time to heart failure. While many mechanistic contributions of PAI-1 to senescence and aging are well documented, its fundamental role in CV aging has not been fully investigated.

Hypothesis: PAI-1 overexpression in mice promotes CV aging, while PAI-1 deficiency attenuates this phenotype in the presence of a stressor.

Methods: To assess the effect of PAI-1 overexpression on CV aging, mice transgenic for a stable variant of human PAI-1 (n=14 transgenics, n=8 wild-type littermates) were characterized at 2 months and 7 months. To assess the effect of PAI-1 deficiency, mice heterozygous for a Serpine1 frame-shifting loss-of-function mutation (n=9) and wild-type littermates (n=10) were assessed; these mice underwent cardiovascular stress using N(ω)-nitro-L-arginine methyl ester (L-NAME) (1mg/L) for 8 weeks. Cardiovascular phenotyping included treadmill, pulse-wave velocity (PWV), echocardiography, and blood pressure (BP) measurement at the beginning and end of study. Histology was performed on aortas using Masson’s Trichome and analyzed for fibrosis quantification.

Results: PAI-1 transgenic mice exhibited worse diastolic (E/e’) and vascular function (PWV, systolic and diastolic BP) compared to their wild-type counterparts. Histology showed more extensive peri-aortic fibrosis. In contrast, PAI-1 loss-of-function heterozygotes were broadly resistant to the vascular aging effects of L-NAME compared to wild-type mice. Molecular profiling of vascular tissues collected from animals is underway and includes bulk aorta RNAseq and measures of epigenetic age.

Conclusion: PAI-1 is necessary and sufficient for the development of a CV aging phenotype in mice while PAI-1 deficiency attenuates stress-induced CV aging. Inhibition of PAI-1 will likely be tested for preventing CV aging in humans.